The invention relates to a magnetic recording and playback device which includes a magnetic head of the type having a tape contact face, and more particularly to such a device including means for guiding, during operation, a magnetic tape along the tape contact face of the magnetic head. The tape is of the type in which a lacquer layer, in which a magnetic pigment is dispersed, is provided on a synthetic carrier. The magnetic head comprises a magnetic core of a metallic material which defines a transducing gap.
It is a known phenomenon that the magnetic heads which are used in magnetic recording and playback devices, for example, tape and cassette recorders, are subject to detrition. Heretofore, it has been assumed that abrasive behavior of the magnetic tape was the main cause of the head detrition and attempts have been made to develop new head materials which are harder and, hence, better able to withstand abrasive detrition. An example of such a new material in Sendust. Unfortunately, however, it has been found that the problem of detrition of the head was not solved by the introduction of harder materials.
From investigations which led to the present invention, it was found that undesired head-tape interactions, particularly, detrition of heads having a magnetic core of a metallic material, are governed to a considerable extent by complex physicalchemical corrosion-like processes. It has been found that various water-soluble chemicals can emanate from the tape. These chemicals may originate from impurities of the oxidic magnetic pigment, from the dispersing agents used, from the binder etc. and in nearly all cases they are of an acidic nature. These chemicals are emitted from the tape under the influence of moisture which is absorbed by the tape to an extent dependent upon the relative humidity and the structure of the lacquer layer. This creates an ideal situation for corrosion of the tape contacting surface of a magnetic head core.